1. Field of the Invention
This invention relates to the field of fluid purification including the field of ultra-pure process gas purification such as those used in the semiconductor industry, and more specifically, to a fluid purification system, and associated methods, utilizing a purifier with a cooler (i.e., a cooled or cryogenic purifier) to remove impurities from a matrix gas with temperature purification or filtering medium or media mixture, such as a high surface area material, maintained at a reduced or low temperature.
2. Description of the Prior Art
There is a growing demand for process gases and other fluids that are almost free of impurities. Many production and other uses of gases require impurities levels, such as moisture levels, to be at or less 10 parts per billion (ppb), and these gases are often considered ultra-pure gases.
The semiconductor industry provides a specific example of the growing demand for ultra-pure process gases or fluids, e.g., matrix gas or fluid that needs to be purified by removing impurities. As semiconductor integrated devices become smaller and the devices using semiconductor integrated devices become more sophisticated, there are increasing demands for the physical and chemical properties of the actual semiconductor material to have properties nearer to the ideal and intrinsic properties of the semiconductor material. The manufacture of semiconductors involves the use of reactive gases that are composed of various elements. In addition, manufacturing processes such as metal-organic chemical vapor deposition (MOCVD) and other related manufacturing techniques are used in the manufacture of semiconductors. In these processes, the purity of the reactive gases plays a large part in determining the resulting quality of the semiconductor device being manufactured, and in particular, the electronic quality and characteristics of the manufactured semiconductor device. Consequently, there is an increasing demand in the microelectronics industry for ultra-pure process gases. The semiconductor industry provides just one example of the increased demand for ultra-pure process gases, and to meet these demands, methods for ultra-purification of gases have experienced extensive technological effort and advances.
Ultra-pure gases are generally produced by processing a matrix or process gas with a purification system that includes a purifier that uses a variety of filtering or purifying media and/or mechanical filters and other devices to remove impurities from the matrix or process gas, e.g., to remove moisture to obtain moisture levels in the matrix or process gas of less than 10 ppb. Presently, most of the research and development efforts have been directed toward producing media for use in the purifier that can effectively remove impurities as the gas (or other fluid) flows through the purifier. High surface area materials are often used as purifier media to create a substrate, such as a substrate of very small beads or the like, that is provided in a purifier canister, and a matrix or process gas is forced to flow through the substrate at a particular flow rate and pressure.
Development efforts have led to purifier media that are capable of removing trace impurities in process fluids to levels well below 1 part per million (ppm) but, in some cases, the adsorption characteristics of the purifier media limit the level of impurity removal that can be achieved by a given purifier medium. For example, some purifier media or material that is used in the semiconductor industry has been tested or shown to be capable of removing moisture from matrix gas (i.e., HCl gas) flowing at ambient temperature and at a pressure of about 30 psig to levels in the range of 150 to 200 ppb. However, these levels do not satisfy the demands of the semiconductor industry which continues to demand moisture levels of 10 ppb or less for many of its processes gases, such as for HCl gas to be used in chamber and wafer cleaning applications.
Hence, there remains a need for improved methods and systems for purifying matrix fluids, such as for producing higher purity gases for use in the semiconductor industry and for many other applications. Preferably, such methods and systems would be configured to meet the increasing demand for ultra-pure gases while also being compatible with many existing gas delivery systems and allow use of many existing purifier media and/or high surface materials.